Why do damping properties of rubber decrease with strain amplitude?

[scriptymender]

Hey Guys,

Can anyone tell me why the damping properties of rubber will decrease as the strain amplitude increases?

Thanks

 

[Lok]

Hi scriptymender,

A quick link to get some fundamentals in place.
http://en.wikipedia.org/wiki/Hysteresis#Hysteresis_in_mechanics

Not sure if you mean compression or tension.

There are a few effects that come in place as rubber gets stretched. Mechanically the speed of propagation of a wave in a string (v) is proportional to the square root of the tension of the string (F) (http://en.wikipedia.org/wiki/Vibrating_string), this affects the interaction time for internal friction and could result in a overall reduction.
A more detailed explanation should require a look on the chemical/physical interactions that take place while the material is compressed or stretched, witch affects molecule alignment (compression stretches and aligns too) and overall Van der Waals interactions.

 

[scriptymender]

Thanks a lot mate, I really appreciate your help!